1. Field of the Invention
The present invention relates generally to an apparatus for starting internal combustion engines. Specifically, the present invention is a starting apparatus that energizes a starter motor and then de-energizes the starter motor once the internal combustion engine begins running. The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the U.S. Department of Energy and Westinghouse Savannah River Company.
2. Discussion of Background
In a typical internal combustion engine, there is a starter motor that is activated by turning the ignition key momentarily until the starter motor causes the engine to start. The starter motor has a flywheel that turns the crankshaft of the engine. As the crankshaft is turned, the pistons connected to the crankshaft compress the air in each of the cylinders in succession. Meanwhile, an air/fuel mixture enters each cylinder and a spark is delivered to the sparkplugs of the cylinder to ignite the mixture. Once the cylinders are all firing, and the engine is running, the starter motor is deactivated. When the internal combustion engine is to be stopped, a signal is sent to the engine's magneto to discontinue the delivery of the voltage to the sparkplugs.
Unfortunately, the starting of the engine is based on hearing it operate. The user knows when the engine has been started by the sound of it running. However, there are occasions when the user cannot hear well enough or not at all. For example, in noisy environments the engine sound may be drowned out by the noise. If the operator has a hearing impairment, the sound of the engine may be inaudible. Also, there are circumstances when an engine might be started remotely. In these circumstances, there is no one present to listen for the engine sound.
There exists in the art a variety of starting apparatus for internal combustion engines. These apparatus typically monitor a particular engine variable until it indicates that the engine has started and then de-energize the starter motor. What follows is a brief review of the art's current state.
One class of device monitors engine speed to determine whether the engine has started, or to regulate its operation. Representative of this class is Chmielewski (U.S. Pat. No. 4,577,599) and Avdenko, et al. (U.S. Pat. No. 3,657,720). Chmielewski mounts a sensing coil adjacent to the flywheel, and reinitiates cranking when the engine speed fails to reach a predetermined level after a predetermined cranking period. Avdenko, et al. monitor the generator output to determine when the engine is turning over at a higher number of revolutions per minute (RPM) than the maximum cranking RPM. Their device stops the engine if running, and starts the engine if stopped.
Several devices teach voltage measurement as a means of controlling the operation of a combustion engine. Chmielewski, Avdenko, et al., and Bean, et al. (U.S. Pat. No. 3,530,846) monitor the generator output voltage to determine engine condition. Ramsperger (U.S. Pat. No. 4,236,594), Biancardi (U.S. Pat. No. 4,227,588), and Weiner (U.S. Pat. No. 3,859,540) monitor the voltage across the alternator, regulator and ignition coil, respectively. Ramsperger energizes the starter motor for a predetermined number of seconds, and checks the status of a relay that is energized by the alternator output to verify that the engine is running. If the engine has not started, the starter motor is re-energized a predetermined number of times, with a predetermined delay between each energizing. Weiner monitors the ignition coil voltage (zero when the engine is off, intermediate during cranking, and higher while the engine is running). Finally, Biancardi opens a switch to disconnect the starter solenoid once the voltage in the regulator stator equals the battery voltage.
The engine oil pressure is used by Tholl, et al (U.S. Pat. No. 4,446,460) and Weiner, both of whom shut off the starter motor once the oil pressure reaches its operating level.
Scott, et al (U.S. Pat. No. 5,054,569), Phairr (U.S. Pat. No. 4,674,454), Parfill (U.S. Pat. No. 2,367,960) and Petric (U.S. Pat. No. 3,603,802) all teach the use of engine vacuum as a means of determining engine status. These designs employ vacuum-activated switches that operate to deactivate the starter motor once the engine is running. Scott, et al. use a microcomputer-based circuit and digital command signals; Parfill connects a vacuum-operated switch to the engine induction pipe, arranged to open the starting motor relay when the engine starts to turn. The Phairr device operates the starter motor for a predetermined period, and, if the engine fails to start, it automatically makes a second attempt to start the engine.
Prior art devices measure engine status using indicators that are somewhat indirect, that is, variables not associated with the status of the starter motor itself. As a result, many of the parameters used by the prior art vary due to extrinsic factors, and therefore erroneous readings are common. For example, the vacuum generated by a running engine may change if there is a leak, and consequently, a device that senses engine vacuum may attempt to restart the engine, causing electrical and mechanical damage. The problems caused by measuring indirect indicators decrease the efficiency and accuracy of combustion engine starters.
Therefore, there is a need for a starter which accurately monitors a simple, direct variable to determine accurately the operating status of an internal combustion engine.